摘要: |
In this research project, asphalt binders containing various polymer modifiers were investigated through examining both binder and mixture properties. Two additional topics were also investigated, including: a) the effects of liquid anti?strip additives on asphalt mixtures; and b) the effects of natural sands in asphalt mixtures. The asphalt binder modifiers in this project included: two plastomers; an elastomer; PPA+SBS; terminally blended ground tire rubber (GTR) binder; and a lab?prepared GTR binder. The binder properties of 16 binder combinations were obtained (e.g., viscosity, DSR, etc.) and compared. In addition, these modified binders were used in mixtures with two aggregate sources, three anti?strip additives, and varying RAP contents. There were 32 different Superpave mix designs conducted for this project. Many engineering properties of the mixtures were obtained, including: indirect tensile strength, tensile strength retained, rutting, and AMPT values. The AMPT testing was conducted at different temperatures and frequencies. The results indicated that, in general, many of the alternate modified binders could be utilized in South Carolina hot mix asphalt (HMA) mixtures. The results also indicated that RAP and natural sand could be utilized, in limited quantities, in many mixtures used on South Carolina secondary roads. In addition, the mixtures made with liquid anti?strip additives in this project in many cases produced moisture susceptibility values (e.g., ITS, TSR) that were compatible with those obtained with mixtures containing hydrated lime. |